1. Field of the Invention
The present invention relates generally to the interconnecting signals between devices and, more specifically, the present invention relates to switching or routing optical signals.
2. Background Information
The need for fast and efficient optical switching devices is increasing as Internet data traffic growth rate is overtaking voice traffic pushing the need for optical communications. Two commonly found types of optical switching devices are mechanical switching devices and electro-optic switching devices.
Mechanical switching devices generally involve physical components that are placed in the optical paths between optical fibers. These components are moved to cause switching action. Micro-electronic mechanical systems (MEMS) have recently been used for miniature mechanical switches. MEMS are popular because they are silicon based and are processed using somewhat conventional silicon processing technologies. However, since MEMS technology generally rely upon the actual mechanical movement of physical parts or components, MEMS are generally limited to slower speed optical applications, such as for example applications having response times on the order of milliseconds.
In electro-optic switching devices, voltages are applied to selected parts of a device to create electric fields within the device. The electric fields change the optical properties of selected materials within the device and the electro-optic effect results in switching action. Electro-optic devices typically utilize electro-optical ceramic materials that combine optical transparency with voltage-variable optical behavior. One typical type of single crystal electro-optical material used in electro-optic switching devices is lithium niobate (LiNbO3).
Lithium niobate is a transparent, material that exhibits electro-optic properties such as the Pockels effect. The Pockels effect is the optical phenomenon in which the refractive index of a medium, such as lithium niobate, varies with an applied electric field. The varied refractive index of the lithium niobate may be used to provide switching. The applied electrical field is provided to present day electro-optical switching devices by external control circuitry.
Although the switching speeds of these types of devices are very fast, for example on the order of nanoseconds, one disadvantage with present day electro-optic switching devices is that these devices generally require relatively high voltages in order to switch optical beams. Consequently, the external circuits utilized to control present day electro-optical switching devices are usually specially fabricated to generate the high voltages and suffer from large amounts of power consumption. In addition, integration of these external high voltage control circuits with present day electro-optical switching devices is becoming an increasingly challenging task as device dimensions continue to scale down and circuit densities continue to increase.
An apparatus and method for switching an optical beam are disclosed. In one embodiment, a presently described optical switching device includes a semiconductor substrate of an integrated circuit die. A first array of capacitors is disposed in the semiconductor substrate. The first array is coupled to receive a signal. The capacitors modulate a charge region in the first array of capacitors in response to the signal. A first optical port is optically coupled to the first array of capacitors through the semiconductor substrate. A second optical port is also optically coupled to the first array of capacitors through the semiconductor substrate. Additional features and benefits of the present invention will become apparent from the detailed description, figures and claims set forth below.